The oil and gas exploration and extraction industry has learned that a percussive or hammer effect tends to increase the drilling rate that is achievable when drilling bores through hard rock. In such drilling operations, drilling fluid or “mud” is pumped from the surface through the drill string to exit from nozzles provided on the drill bit. The flow of fluid from the nozzles assists in dislodging and clearing material from the cutting face and serves to carry the dislodged material through the drilled bore to the surface. It has been recognized that providing a pulsing fluid flow from the nozzles may also serve to increase the drilling.
The industry has also learned that pulsation or agitation during directional drilling may have a similar beneficial effect, reducing stick-slip of the drill string in the directional wellbore, and improving weight transfer to the bit.